To optimise recovery, the oil industry depends on gathering data from wells and reservoirs. These data form the basis for nearly every decision with respect to the development and operation of an oil field, including where to locate new wells, maintenance programs and allocation/control of production.
Because of this need for data, many well applications of today are completed with permanently installed pressure and temperature monitoring devices. Most systems available in today's market require electrical supply and communication lines running the length of the downhole pipe from the wellhead down to the downhole gauge (i.e. downhole completion), usually secured by using clamps fitted onto the tubing. Fitting cables to the tubing (completion) is a time consuming activity that lengthen the installation time compared with tubing installation without downhole gauges. During the installation of traditional gauges, the cables, clamps, splices, penetrators and/or connectors are greatly exposed and are natural failure mechanisms. If damage occurs, the worst-case scenario is that the entire length of tubing must be retrieved to replace a damaged cable. If the damaged equipment is repairable downhole, a well service operation must be performed.
Other borehole devices, such as multiphase flow meters, sand detectors, valves, chokes, circulation devices (final elements), and similar are less commonly installed as part of a permanent borehole completion, but where this is the case, the same problems as described above apply.
Permanently installed data acquisition devices often suffer from a significant degree of failure, and this leads to limited obtainable information from the reservoir. This may have a serious impact on the understanding and modelling of the reservoir and reduce the reservoir recovery factor.
Due to harsh environment and high temperatures in the well, such instrumentation has limited lifetime expectancy and traditionally fails due to long-term failure mechanisms and technology misuse. Depending on the well conditions, the lifetime of this technology varies from a few months to a few years. There is therefore a need for methods and systems, which allow monitoring when the permanent monitoring systems have failed, thus regaining/maintaining the continuity of dataflow from the well. Preferably, the replacement/remedial method should be intervenable by means of well service techniques and not require re-completing the well.
Also, in particular for shallow-water and land-market oil and gas wells, cost effective alternatives to cable-based permanent instrumentation is considered very attractive. Hence, the invention and the technology can be applied both as a replacement for failed cable-based systems or as a stand-alone, preferred data acquisition solution for smaller, fairly low-producing fields.